1. Technical Field
The present invention relates to a projector.
2. Related Art
There is a known projector of related art in which light outputted from a light source apparatus is modulated by a light modulator in accordance with image information and the modulated light is projected through a projection lens onto a projection surface.
JP-A-2013-88743 discloses a projector including a controller having a normal mode in which a light source and a light modulator are cooled by controlling the speed of rotation of a cooling fan and an auxiliary mode in which the speed of rotation of the cooling fan is controlled to differ from the speed of rotation in the normal mode based on the temperature in an exterior enclosure after the projector is activated. In a situation in which constituent members of the projector expand due to an increase in the temperature of the light source and therefore shift a projection position, the configuration described above quickly achieves a balanced state in the enclosure by using the auxiliary mode to shorten the period required to adjust the projection position.
FIGS. 7A and 7B are cross-sectional views diagrammatically showing a schematic configuration of a projector 9 of related art. FIG. 7A shows a state immediately after projection starts, and FIG. 7B shows a state during the projection.
The projector 9 of related art includes an illumination unit 90, which has an optical system including a light source apparatus 901, an image formation unit 91, which has an optical system including a light modulator 911, and a projection unit 92, which has an optical system including a projection lens 921, as shown in FIGS. 7A and 7B. The image formation unit 91 is coupled to the projection unit 92, and the projection unit 92 to which the image formation unit 91 is coupled is coupled to the illumination unit 90. A plurality of fixing portions 902, which are formed all around the exterior of the illumination unit 90, fix the illumination unit 90 to an exterior enclosure 93, which forms the exterior of the projector 9, directly or indirectly via interposed members. Further, legs 94 for placing the projector 9 on a desktop are fixed to the exterior enclosure 93. The exterior enclosure 93 is formed of a synthetic resin member.
In general, a projector has a heat generation source, such as a power supply and a light source apparatus. After the light source apparatus is turned on to start projection, the temperature of each constituent member that forms the projector gradually increases from a start temperature equal to the temperature in the environment where the projector is installed. Each constituent member that forms the projector is primarily made of a synthetic resin and therefore expands/contracts as the temperature changes, and the modulus of elasticity of the synthetic resin also changes with temperature.
In the projector 9 immediately after the projection starts, the temperature of each constituent member is equal to the temperature in the environment, and the constituent member does not deform or otherwise change and is held in an intended position thereof, as shown in FIG. 7A. In this state, an image (modulated light) is precisely projected in a projection position set on a screen (not shown).
In the configuration of related art, however, after time elapses from the start of projection, each constituent member in the projector 9 experiences an increase in temperature and expands, and the modulus of elasticity of the constituent member also changes, resulting in deformation of the constituent member, as shown in FIG. 7B. Specifically, in the projector 9, the increase in temperature causes the illumination unit 90, the image formation unit 91, and the projection unit 92 to expand and the modulus of elasticity thereof to decrease. The illumination unit 90 deforms while restricted (constrained) by the fixing portions 902, which are fixed to the exterior enclosure 93. On the other hand, the image formation unit 91 and the projection unit 92 deform while fixed to (constrained by) the deforming illumination unit 90. In this case, the image formation unit 91 and the projection unit 92 undesirably deform downward (toward desktop on which projector 9 is installed) also due, for example, to their own weights. The position of an image projected on the projection surface (projected image) therefore undesirably shifts from a predetermined position (shift in projection position).
Further, the projector 9 is installed with the legs 94 fixed to the exterior enclosure 93. Therefore, when the exterior enclosure 93 expands and the modulus of elasticity thereof decreases as the temperature increases, the exterior enclosure 93 deforms relative to the legs 94. As a result, the position of the illumination unit 90, which is fixed to (constrained by) the exterior enclosure 93 also changes, and the positions of the image formation unit 91 and the projection unit 92, which are fixed to (constrained by) the illumination unit 90, undesirably further change. The position of the projected image therefore undesirably further shifts from the predetermined position (shift in projection position).
A projector that suppresses shift in the projection position due to a change in temperature has therefore been desired.